chriscarrere

Ever since I changed heads and cam I've had valves train problems. First time I turned it maybe 6200 and heard a rattling. I pulled a valve cover and the roller rocker hit the ground. Found a lifter apart and the rocker stud broken. I replaced the broken parts and about 4 months later turned it maybe 6200 again and started rattling again. Found another comp lifter coming apart. I'm thinking maybe cam lift is too much for my springs. I have xfi292 with AFR 195 eliminator heads with the .600 lift springs. What do ya'll think. Change the springs for more lift?

SS RRR

iTrader: (2)

Do you have an exact part number for the springs? Comp R lifters?

96capricemgr

iTrader: (1)

The XFI lobes can be hard to control with standard springs, part of the design of those lobes was being able to make use of lightweight beehive springs.

I find several things in your post very worrysome. First you want to blame lifters so it sounds like you really don't understand the system, when the rocker stud breaks the lifter is easily thrown out of it's bore, the lifter is pretty obviously a result of another failure there. Then you bought a cam that needs 7000rpm in a 350 and even a solid 6500+ in a 396but are only occasionally taking it to 6200 and the setup is bad enough it wont stay together.

AFR at times has had a lot of problems with **** chinese rocker studs. Could have saved yourself a lot of problems coming here for advise first rather than doing a magazine/catalog build that cost too much and doesn't work.

How heavy are the valves in those heads? If they are a fair bit lighter than the LT1 stock valves you could maybe try the 918 beehives Comp recommends, if they are similar to LT1 weight or heavier you will definitely need more spring start looking at a stiffer beehive from another company.

Comp's spring recommendations are often marginal on LT1s because they use gen 1 duration to rpm numbers but the LT1 intake shifts the rpm range up. You bought a cam Comp rates to 6200rpm BUT guys have found it to peak anywhere from 6500- over 7000rpms on 350s depending on the heads/intake package.

IMO get new studs and a beehive stiffer then the 918 Comp specs, check the seals/pushrods/lifters and replace as necessary and hopefully this can be bandaided back together.

chriscarrere

I've already replaced the studs and full set of lifters and cam is the one recommended by comp. I'm looking at replacing the springs with either the comp 918 or the upgrade from afr which is the patriot gold.

chriscarrere

Yeah I realize I jumped the gun on the spring choice from the get go. I'm not blaming the lifters I think the problem is in the springs. It had comp lifters which I've read have had problems. I've since changed to ls7. The valves are supposed to be a lightweght one so if that is true which should I go with the comp 918?

4K+Converter

Another thing to check is that your setting the proper valve lash. When I had my old cc306 car, I couldn't accurately tell by looking at the valves where tdc was. Thus my rockers would go loose after a mile or so. I had to take the #1 spark plug out and feel with a screw driver when it hit tdc.

As for spring pressure, your cam card should tell you what open and closed seat pressure your springs need to have. There are more considerations than that too. Double check with comp. if you haven't upgraded your push rods, they might go next with all the added pressure.

chriscarrere

All installation in being done by some friends with alot of knowledge. But the parts were done with advice from yeah I know the manufacturers. Friends have cars in the 4's in the 1/8 so I think the installation is fine. The push rods are comp hi-techs so they "should" be ok. The thing is it went almost a year before the first problem. Just shows up when it's turned up. When it's right the car runs strong just tired of the problems of the 93 lt1. I know these problems are because of my choices but you live and learn.

96capricemgr

iTrader: (1)

The Comp recommendation was done by someone reading the catalog with the WRONG RPM RANGES for you. Their "tech line" is people reading a catalog, no actual knowledge there. To make that point a LOT of us use cams around 228degrees for intake duration and have them peak at 64-6500rpm and make power all the way to 7000rpm. Does that make a point of just how inaccurate the 6200rpm rating on your 242duration cam is? One guy here with Lingefelter ported LT1 heads had that cam still climbing at 7000rpm when his pcm peaked out. To make proper use of a cam it is common to turn 400rpm past peak.
The 918s are wrong be cause of the above mentioned rpm range inaccuracy.
Patriot folded, don't think you are going to be going with those. Besides I already told you the XFI lobes can be tough to control with a heavy dual spring and were designed with beehives in mind. I am sure that you can find a dual to work but you are going to have to involve a valvetrain vendor who understands the LT1 rpm ranges for a given cam




I did a little googling and can't find an actual number on the valve weight. I would go something stiffer then the 918, the AFR valves are thin stem but larger diameter so it is unlikely they would be sufficiently light to allow the RPM you need to actually use that cam.

chriscarrere

Thanks for all the info. Do you happen to have a part number for a spring you would recommend.

chriscarrere

I'm am planning to bigger ci soon so alittle bigger cam for now I'm ok with.